tsdb: add chunk_encoding config field for runtime encoding selection by roidelapluie · Pull Request #18769 · prometheus/prometheus

roidelapluie · 2026-05-22T15:41:19Z

Add a new storage.tsdb.chunk_encoding.floats configuration field that allows operators to select the float chunk encoding (xor or xor2) independently of the --enable-feature=xor2-encoding startup flag.

When the field is absent the encoding follows the feature flag as before. Setting xor forces standard XOR encoding even when the feature flag is set. Setting xor2 is only valid when the feature flag is set, and Prometheus will refuse to reload the config otherwise. The field is runtime-reloadable.

Add chunkenc.Compatible(a, b Encoding) to express that EncXOR and EncXOR2 are interchangeable at append time when ST (start-timestamp) storage is disabled. The appendPreprocessor in head_append.go uses this to avoid cutting an in-progress chunk on an encoding change; the new encoding takes effect at the next natural chunk boundary. When ST storage is enabled, the two encodings are not compatible because XOR chunks do not store start timestamps, so the chunk is cut immediately on the next append.

Propagate storeST through chunkOpts so that both WAL and WBL replay paths correctly apply the ST-storage compatibility rule when restoring chunks.

Release notes for end users (ALL commits must be considered).

Reviewers should verify clarity and quality.

[FEATURE] TSDB: Add `storage.tsdb.chunk_encoding.floats` configuration field to select float chunk encoding (`xor` or `xor2`) at runtime, independently of the `--enable-feature=xor2-encoding` flag.

--enable-feature=xor2-encoding sets tsdb.Options.FloatChunkEncoding to EncXOR2 (a concrete encoding value, not a feature-flag bool). ApplyConfig uses this as the fallback when chunk_encoding.floats is absent. No global mutable state is introduced in the config package. Signed-off-by: Julien Pivotto <[email protected]> Signed-off-by: Julien Pivotto <[email protected]>

krajorama

Minor comments, plus we need to work out the implications for the histograms ST chunks.

- Rename chunkenc.Compatible to CompatibleValues and document that it concerns sample-value encoding only; ST compatibility is the caller's responsibility. Update callers and tests. - Use audience-neutral wording in validateOpts errors (the tsdb package is also consumed as a library) instead of Prometheus-only config-key names. - Correct docs/feature_flags.md: with st-storage active and a resolved XOR encoding, Prometheus fails configuration validation rather than warning. - Drop the unrelated LICENSE-check change from scripts/sync_repo_files.sh. Signed-off-by: Julien Pivotto <[email protected]>

krajorama

Approved with nit + WAL without ST -> load with XOR2 is tested, but the reverse isn't . WAL has ST, but loaded with XOR. Probably not important.

…➔ v3.13.0) (#1360) This PR contains the following updates: | Package | Update | Change | |---|---|---| | [quay.io/prometheus/prometheus](https://github.com/prometheus/prometheus) | minor | `v3.12.0` → `v3.13.0` | --- ### Release Notes <details> <summary>prometheus/prometheus (quay.io/prometheus/prometheus)</summary> ### [`v3.13.0`](https://github.com/prometheus/prometheus/releases/tag/v3.13.0): 3.13.0 / 2026-07-01 [Compare Source](prometheus/prometheus@v3.12.0...v3.13.0) This is a Long Term Support [LTS](https://prometheus.io/docs/introduction/release-cycle/) release. - \[SECURITY] UI: Bump `sanitize-html` to fix a cross-site scripting vulnerability (CVE-2026-44990). [#18697](prometheus/prometheus#18697) - \[CHANGE] UI: Third-party npm dependency licenses are now embedded in the Prometheus binary and served at `/assets/third-party-licenses.txt`, replacing the `npm_licenses.tar.bz2` archive previously shipped in release tarballs and container images. [#18997](prometheus/prometheus#18997) - \[CHANGE] API: Use SHA-256 instead of SHA-1 to generate rule group pagination tokens. [#18927](prometheus/prometheus#18927) - \[CHANGE] HTTP clients: Credentials (Authorization header, basic auth, bearer token, OAuth2, configured headers) are no longer forwarded when following a redirect to a different host; affects scraping, remote read/write, alerting, and service discovery. Via prometheus/common v0.69.0 (CVE-2025-4673 CVE-2023-45289). [#18949](prometheus/prometheus#18949) - \[CHANGE] promtool: Relative file paths in the file passed to `--http.config.file` are now resolved relative to that config file's directory instead of its parent directory. Via prometheus/common v0.69.0. [#18949](prometheus/prometheus#18949) - \[CHANGE] PromQL: Rename the `min()` and `max()` duration-expression functions (experimental feature flag `experimental-duration-expr`) to `min_of()` and `max_of()` to avoid confusion with the `min` and `max` aggregate operators. [#18687](prometheus/prometheus#18687) - \[FEATURE] API: Add experimental search endpoints to search metric names, label names, and label values. [#18573](prometheus/prometheus#18573) - \[FEATURE] Discovery/AWS: Add ability to filter RDS instances. [#18859](prometheus/prometheus#18859) - \[FEATURE] PromQL: Add `min_of(a, b)` and `max_of(a, b)` scalar experimental functions, returning the smaller or larger of two scalar values. [#18687](prometheus/prometheus#18687) - \[FEATURE] PromQL: Add support for smoothed/anchored rate with native histograms. [#18564](prometheus/prometheus#18564) - \[FEATURE] PromQL: Expose per-query `samplesRead` (and `samplesReadPerStep` with `stats=all` and the `promql-per-step-stats` feature flag) in the query stats response, and add the `prometheus_engine_query_samples_read_total` engine counter. `samplesRead` reflects storage I/O distinct from `totalQueryableSamples`, which counts samples loaded into the evaluator (and so over-counts when a sample is reused across multiple range-vector windows). [#18081](prometheus/prometheus#18081) - \[FEATURE] Scrape: Add `__convert_classic_histograms_to_nhcb__` internal label to allow per-target override of `convert_classic_histograms_to_nhcb` scrape configuration via relabeling. [#18840](prometheus/prometheus#18840) - \[FEATURE] TSDB: Add `storage.tsdb.chunk_encoding.floats` configuration field to select float chunk encoding (`xor` or `xor2`) at runtime, independently of the `--enable-feature=xor2-encoding` flag. [#18769](prometheus/prometheus#18769) - \[FEATURE] remote\_write: Add Certificate support for ingesting data into an Azure Monitor Workspace. [#18217](prometheus/prometheus#18217) - \[FEATURE] Scrape: Add `__always_scrape_classic_histograms__` and `__scrape_native_histograms__` internal labels to allow per-target override of the `always_scrape_classic_histograms` and `scrape_native_histograms` scrape configuration via relabeling. [#18929](prometheus/prometheus#18929) - \[ENHANCEMENT] Release: Container images are now also published to the GitHub Container Registry (ghcr.io). [#18791](prometheus/prometheus#18791) - \[ENHANCEMENT] PromQL: Prettify `fill_left(x) fill_right(x)` as `fill(x)` when both fill values are equal. [#18851](prometheus/prometheus#18851) - \[ENHANCEMENT] UI: Improve autocompletion after closing a function bracket. [#18894](prometheus/prometheus#18894) - \[PERF] Labels: Add case-insensitive prefix matching to speed up evaluation of long case-insensitive regular expressions (up to \~2x faster). [#18540](prometheus/prometheus#18540) - \[PERF] TSDB: Reduce per-sample overhead in chunk population, speeding up affected queries by \~12-15% in benchmarks. [#18699](prometheus/prometheus#18699) - \[PERF] TSDB: Eliminate unnecessary heap allocations in the V2 histogram WAL decoder, reducing allocations by up to 50% and memory by up to 10% for deployments using native histograms with created-timestamp storage enabled (`--enable-feature=created-timestamp-zero-ingestion`). [#18813](prometheus/prometheus#18813) - \[BUGFIX] Discovery/AWS: Fix failure when processing an AWS RDS cluster without instances. [#18845](prometheus/prometheus#18845) - \[BUGFIX] Fix race condition in initTime that could cause ErrOutOfBounds. [#18629](prometheus/prometheus#18629) - \[BUGFIX] PromQL: A range query whose `end` was not aligned to `step` caused subqueries inside it to evaluate past the parent's last actual step, inflating `peakSamples` in the query stats and against the `query.max-samples` limit, and wasting storage I/O reading samples that were never used in the result. [#18081](prometheus/prometheus#18081) - \[BUGFIX] PromQL: A range query containing an at-modifier-unsafe function over a range-vector with an `@` modifier (e.g. `predict_linear(metric[60s] @ T, X)`) silently under-counted `totalQueryableSamples` for steps after step 0. [#18081](prometheus/prometheus#18081) - \[BUGFIX] PromQL: Fix `fill_left`/`fill_right` producing missing samples in range queries when using `group_left`/`group_right`. [#18850](prometheus/prometheus#18850) - \[BUGFIX] PromQL: Fix for resets() and changes() in anchored range extenders with histograms. [#18906](prometheus/prometheus#18906) - \[BUGFIX] PromQL: Fix panic on `1[5m] smoothed` and similar expressions when extended range selectors are enabled. [#18764](prometheus/prometheus#18764) - \[BUGFIX] PromQL: Fix panic when a `smoothed` instant vector selector produces no samples for a series. [#18943](prometheus/prometheus#18943) - \[BUGFIX] PromQL: Fix panic when using a parenthesised plain number as an offset (e.g. `foo offset -(5)`). [#18768](prometheus/prometheus#18768) - \[BUGFIX] promtool: Fix panic when parsing exposition text containing empty braces `{}`. Via prometheus/common v0.69.0. [#18949](prometheus/prometheus#18949) - \[BUGFIX] Promtool: Fix `check healthy` and `check ready` when `--url` ends with a trailing slash. [#18854](prometheus/prometheus#18854) - \[BUGFIX] Rules: Close PromQL query after each rule evaluation to ensure resources are released. [#18733](prometheus/prometheus#18733) - \[BUGFIX] Scaleway SD: Resolve VPC/IPAM-only instances that have no legacy `private_ip` or `public_ip` field, but do have private NICs attached. [#18772](prometheus/prometheus#18772) - \[BUGFIX] TSDB: Do not leak head series when an integer histogram append is rejected (e.g. out-of-order). [#18838](prometheus/prometheus#18838) - \[BUGFIX] UI: Escape label values offered by PromQL autocomplete. [#18658](prometheus/prometheus#18658) - \[BUGFIX] TSDB: Fix chunk snapshot encoding for EncXOR2 chunks, preventing corruption on TSDB restart when EncXOR2-encoded series were present. [#18739](prometheus/prometheus#18739) - \[BUGFIX] TSDB: Store a millisecond timestamp (not a WAL segment number) in walExpiries when a series is evicted via CompactStaleHead/CompactSelectedSeries, so the series's label record is correctly retained in the next WAL checkpoint and replays cleanly. [#18847](prometheus/prometheus#18847) - \[BUGFIX] TSDB: Prevent loss of samples at the chunk-range boundary when CompactSelectedSeries (and CompactStaleHead) evict the series — the per-slice compaction loop now runs one more iteration so the boundary timestamp is captured in a block before the in-memory copy is removed. [#18849](prometheus/prometheus#18849) </details> --- ### Configuration 📅 **Schedule**: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined). 🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied. ♻ **Rebasing**: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox. 🔕 **Ignore**: Close this PR and you won't be reminded about these updates again. --- - [ ] If you want to rebase/retry this PR, check this box --- This PR has been generated by [Renovate Bot](https://github.com/renovatebot/renovate).  Reviewed-on: https://git.erwanleboucher.dev/eleboucher/homelab/pulls/1360

##### [\`v3.13.0\`](https://github.com/prometheus/prometheus/releases/tag/v3.13.0) This is a Long Term Support [LTS](https://prometheus.io/docs/introduction/release-cycle/) release. - \[SECURITY] UI: Bump `sanitize-html` to fix a cross-site scripting vulnerability (CVE-2026-44990). [#18697](prometheus/prometheus#18697) - \[CHANGE] UI: Third-party npm dependency licenses are now embedded in the Prometheus binary and served at `/assets/third-party-licenses.txt`, replacing the `npm_licenses.tar.bz2` archive previously shipped in release tarballs and container images. [#18997](prometheus/prometheus#18997) - \[CHANGE] API: Use SHA-256 instead of SHA-1 to generate rule group pagination tokens. [#18927](prometheus/prometheus#18927) - \[CHANGE] HTTP clients: Credentials (Authorization header, basic auth, bearer token, OAuth2, configured headers) are no longer forwarded when following a redirect to a different host; affects scraping, remote read/write, alerting, and service discovery. Via prometheus/common v0.69.0 (CVE-2025-4673 CVE-2023-45289). [#18949](prometheus/prometheus#18949) - \[CHANGE] promtool: Relative file paths in the file passed to `--http.config.file` are now resolved relative to that config file's directory instead of its parent directory. Via prometheus/common v0.69.0. [#18949](prometheus/prometheus#18949) - \[CHANGE] PromQL: Rename the `min()` and `max()` duration-expression functions (experimental feature flag `experimental-duration-expr`) to `min_of()` and `max_of()` to avoid confusion with the `min` and `max` aggregate operators. [#18687](prometheus/prometheus#18687) - \[FEATURE] API: Add experimental search endpoints to search metric names, label names, and label values. [#18573](prometheus/prometheus#18573) - \[FEATURE] Discovery/AWS: Add ability to filter RDS instances. [#18859](prometheus/prometheus#18859) - \[FEATURE] PromQL: Add `min_of(a, b)` and `max_of(a, b)` scalar experimental functions, returning the smaller or larger of two scalar values. [#18687](prometheus/prometheus#18687) - \[FEATURE] PromQL: Add support for smoothed/anchored rate with native histograms. [#18564](prometheus/prometheus#18564) - \[FEATURE] PromQL: Expose per-query `samplesRead` (and `samplesReadPerStep` with `stats=all` and the `promql-per-step-stats` feature flag) in the query stats response, and add the `prometheus_engine_query_samples_read_total` engine counter. `samplesRead` reflects storage I/O distinct from `totalQueryableSamples`, which counts samples loaded into the evaluator (and so over-counts when a sample is reused across multiple range-vector windows). [#18081](prometheus/prometheus#18081) - \[FEATURE] Scrape: Add `__convert_classic_histograms_to_nhcb__` internal label to allow per-target override of `convert_classic_histograms_to_nhcb` scrape configuration via relabeling. [#18840](prometheus/prometheus#18840) - \[FEATURE] TSDB: Add `storage.tsdb.chunk_encoding.floats` configuration field to select float chunk encoding (`xor` or `xor2`) at runtime, independently of the `--enable-feature=xor2-encoding` flag. [#18769](prometheus/prometheus#18769) - \[FEATURE] remote\_write: Add Certificate support for ingesting data into an Azure Monitor Workspace. [#18217](prometheus/prometheus#18217) - \[FEATURE] Scrape: Add `__always_scrape_classic_histograms__` and `__scrape_native_histograms__` internal labels to allow per-target override of the `always_scrape_classic_histograms` and `scrape_native_histograms` scrape configuration via relabeling. [#18929](prometheus/prometheus#18929) - \[ENHANCEMENT] Release: Container images are now also published to the GitHub Container Registry (ghcr.io). [#18791](prometheus/prometheus#18791) - \[ENHANCEMENT] PromQL: Prettify `fill_left(x) fill_right(x)` as `fill(x)` when both fill values are equal. [#18851](prometheus/prometheus#18851) - \[ENHANCEMENT] UI: Improve autocompletion after closing a function bracket. [#18894](prometheus/prometheus#18894) - \[PERF] Labels: Add case-insensitive prefix matching to speed up evaluation of long case-insensitive regular expressions (up to \~2x faster). [#18540](prometheus/prometheus#18540) - \[PERF] TSDB: Reduce per-sample overhead in chunk population, speeding up affected queries by \~12-15% in benchmarks. [#18699](prometheus/prometheus#18699) - \[PERF] TSDB: Eliminate unnecessary heap allocations in the V2 histogram WAL decoder, reducing allocations by up to 50% and memory by up to 10% for deployments using native histograms with created-timestamp storage enabled (`--enable-feature=created-timestamp-zero-ingestion`). [#18813](prometheus/prometheus#18813) - \[BUGFIX] Discovery/AWS: Fix failure when processing an AWS RDS cluster without instances. [#18845](prometheus/prometheus#18845) - \[BUGFIX] Fix race condition in initTime that could cause ErrOutOfBounds. [#18629](prometheus/prometheus#18629) - \[BUGFIX] PromQL: A range query whose `end` was not aligned to `step` caused subqueries inside it to evaluate past the parent's last actual step, inflating `peakSamples` in the query stats and against the `query.max-samples` limit, and wasting storage I/O reading samples that were never used in the result. [#18081](prometheus/prometheus#18081) - \[BUGFIX] PromQL: A range query containing an at-modifier-unsafe function over a range-vector with an `@` modifier (e.g. `predict_linear(metric[60s] @ T, X)`) silently under-counted `totalQueryableSamples` for steps after step 0. [#18081](prometheus/prometheus#18081) - \[BUGFIX] PromQL: Fix `fill_left`/`fill_right` producing missing samples in range queries when using `group_left`/`group_right`. [#18850](prometheus/prometheus#18850) - \[BUGFIX] PromQL: Fix for resets() and changes() in anchored range extenders with histograms. [#18906](prometheus/prometheus#18906) - \[BUGFIX] PromQL: Fix panic on `1[5m] smoothed` and similar expressions when extended range selectors are enabled. [#18764](prometheus/prometheus#18764) - \[BUGFIX] PromQL: Fix panic when a `smoothed` instant vector selector produces no samples for a series. [#18943](prometheus/prometheus#18943) - \[BUGFIX] PromQL: Fix panic when using a parenthesised plain number as an offset (e.g. `foo offset -(5)`). [#18768](prometheus/prometheus#18768) - \[BUGFIX] promtool: Fix panic when parsing exposition text containing empty braces `{}`. Via prometheus/common v0.69.0. [#18949](prometheus/prometheus#18949) - \[BUGFIX] Promtool: Fix `check healthy` and `check ready` when `--url` ends with a trailing slash. [#18854](prometheus/prometheus#18854) - \[BUGFIX] Rules: Close PromQL query after each rule evaluation to ensure resources are released. [#18733](prometheus/prometheus#18733) - \[BUGFIX] Scaleway SD: Resolve VPC/IPAM-only instances that have no legacy `private_ip` or `public_ip` field, but do have private NICs attached. [#18772](prometheus/prometheus#18772) - \[BUGFIX] TSDB: Do not leak head series when an integer histogram append is rejected (e.g. out-of-order). [#18838](prometheus/prometheus#18838) - \[BUGFIX] UI: Escape label values offered by PromQL autocomplete. [#18658](prometheus/prometheus#18658) - \[BUGFIX] TSDB: Fix chunk snapshot encoding for EncXOR2 chunks, preventing corruption on TSDB restart when EncXOR2-encoded series were present. [#18739](prometheus/prometheus#18739) - \[BUGFIX] TSDB: Store a millisecond timestamp (not a WAL segment number) in walExpiries when a series is evicted via CompactStaleHead/CompactSelectedSeries, so the series's label record is correctly retained in the next WAL checkpoint and replays cleanly. [#18847](prometheus/prometheus#18847) - \[BUGFIX] TSDB: Prevent loss of samples at the chunk-range boundary when CompactSelectedSeries (and CompactStaleHead) evict the series — the per-slice compaction loop now runs one more iteration so the boundary timestamp is captured in a block before the in-memory copy is removed. [#18849](prometheus/prometheus#18849)

roidelapluie force-pushed the roidelapluie/xor2-reload branch 3 times, most recently from 7a57ade to ee72ccd Compare June 2, 2026 16:07

roidelapluie changed the title ~~tsdb: add float_chunk_encoding config field for runtime encoding selection~~ tsdb: add chunk_encoding config field for runtime encoding selection Jun 2, 2026

roidelapluie force-pushed the roidelapluie/xor2-reload branch 2 times, most recently from 920d131 to 1bc7409 Compare June 3, 2026 09:31

roidelapluie marked this pull request as ready for review June 3, 2026 09:31

roidelapluie requested review from a team, bwplotka, codesome, jesusvazquez and krajorama as code owners June 3, 2026 09:31

roidelapluie force-pushed the roidelapluie/xor2-reload branch from 3f51e57 to bfadf25 Compare June 4, 2026 15:17

roidelapluie force-pushed the roidelapluie/xor2-reload branch from bfadf25 to 350685b Compare June 11, 2026 14:45

krajorama mentioned this pull request Jun 12, 2026

Add histogram chunk encoding with Start Timestamp support #18609

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roidelapluie enabled auto-merge June 12, 2026 11:50

roidelapluie merged commit aa77834 into prometheus:main Jun 12, 2026
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dongjiang1989 mentioned this pull request Jul 6, 2026

feat: add chunkEncoding field to TSDBSpec for runtime float encoding selection prometheus-operator/prometheus-operator#8675

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github-actions Bot mentioned this pull request Jul 24, 2026

Update prom/prometheus Docker tag to v3.13.1 claytono/infra#2595

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tsdb: add chunk_encoding config field for runtime encoding selection#18769

tsdb: add chunk_encoding config field for runtime encoding selection#18769
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